Plungers for intraocular lens injectors

ABSTRACT

An intraocular lens (IOL) injector for delivering an IOL into an eye of a patient. The injector includes an IOL load chamber and connected delivery tube, and a push rod for urging the IOL through the delivery tube and out of a distal tip thereof. The push rod is guided and biased against one side of the injector load chamber. The injector may include an inflatable pusher for urging the IOL through the delivery tube and out of a distal tip thereof. The inflatable pusher has a proximal end that may be open to an internal cavity of the injector, wherein a plunger movable in the injector cavity forces fluid such as air or saline into the pusher. A distal end of the pusher may be forked to capture a trailing end of the IOL, or may have a bulbous configuration to ensure the pusher does not pass the IOL.

FIELD OF THE INVENTION

The present invention relates to systems and methods for delivering anintraocular lens (IOL) into an eye through an injector/cartridge and,more particularly, to plungers for urging an IOL through aninjector/cartridge.

BACKGROUND OF THE INVENTION

It is estimated that 73% of Americans between the ages of 65 to 74 getcataracts. A cataract is a clouding of the eye's lens that impairs aperson's vision and, if left untreated, causes blindness. As a result,each year approximately 1.4 million people in the United States aloneundergo cataract surgery, whereby the clouded natural crystalline lensis removed and replaced with an intraocular lens (IOL) implant.

Surgeons implant IOLs not only as a replacement for the naturalcrystalline lens but also to alter the optical properties of (providevision correction to) an eye in which the natural lens remains. IOLsoften include an optically clear disk-like optic of about 6 mm indiameter, and preferably at least one flexible fixation member or hapticwhich extends radially outward from the optic and becomes affixed in theeye to secure the lens in position. Implantation of such IOLs into theeye involves making an incision through the cornea. It is advantageous,to reduce trauma and increase the speed of healing, to have an incisionsize as small as possible.

The optics may be constructed of rigid biocompatible materials such aspolymethyl methacrylate (PMMA) or deformable materials such as siliconepolymeric materials, acrylic polymeric materials, hydrogel polymericmaterials, and the like. The deformable materials allow the IOL to berolled or folded for insertion through an injector or insertioncartridge and an incision into the eye. Once within the chamber of theeye, the IOL is expulsed from the injector and returns to its originalshape. The primary deformable IOL materials are silicone and acrylic(hydrophobic and hydrophilic). Silicone IOLs are in general more pliableand can be folded into smaller tubes without unduly stressing theinsertion cartridge or requiring excessive push force, which cansuddenly expel the IOL from the cartridge. Acrylic lenses are insertedin much the same way as silicone IOLs, although in general using largerbore cartridges to mitigate the problems caused by the typically lowerflexibility of the acrylic. Because the cartridge bore is larger, theincision is also necessarily larger, though some acrylics are implantedthrough micro incisions (<2 mm).

Injectors for delivering IOLs into the eye typically employ a handpieceand a removable cartridge that receives the IOL and has a hollowinsertion tube or cannula through which the folded IOL is passed using apush rod. Some injectors do without the cartridge and are reusable. TheIOL is stored separately and transferred to a load chamber in theinjector or cartridge just prior to delivery. One particularly usefularrangement wherein the cartridge folds over an IOL is disclosed in U.S.Pat. No. 4,681,102 to Bartell. A cartridge opens to receive an IOL in aload chamber, and then folds closed and fits into an injector. Asyringe-like plunger in the injector pushes the IOL from the loadchamber through a tapered tube into the eye. The IOL unfolds as itemerges from the tip of the tapered tube. Another such insertion systemis disclosed in Makker et al., U.S. Pat. No. 5,942,277.

The goal of achieving safer cataract surgery and reduced patientrecovery time has resulted in smaller and smaller incisions, often lessthan 3 mm. Because the tip diameter of the injector or cartridge must bereduced accordingly, the IOL must likewise assume a smaller profile asit passes into the eye. This increases the force required to push theIOL through the small cartridge lumen, and impacts on the dynamicsbetween the plunger and the IOL. Even with the introduction of aviscoelastic medium therebetween, the forces required to push the IOLagainst friction through the cartridge sometimes result in the push rodriding over the IOL, pinning one of the haptics against the inner lumenof the cartridge, or damaging to the trailing edge of the IOL.

Moreover, the IOL is deformable so the point where it is engaged mayshift if the push rod does not have sufficient lateral stiffness.Likewise, the deformed shape of the IOL may result in a reaction forceon the plunger with a force component in a lateral direction thatdisplaces the push rod, causing it to bypass the IOL. Although onesolution is to stiffen the push rod by increasing its cross-section, andreducing its length, these are not practical modifications as they runcounter to the desire for a small and often elongated cartridge lumen.

One attempt to maintain contact between a plunger and IOL is seen inU.S. Pat. No. 5,494,484 to Feingold, which discloses a plunger having afaceted tip configured to engage the trailing edge of the IOL optic.U.S. Pat. No. 6,010,510 to Brown, et al. includes an injector having aplunger with an offset tip. The tip flexes up onto the floor of thecartridge so that there is a constant downward bias and the tip does notride over the IOL. U.S. Pat. No. 6,558,395 to Hjertman discloses aninsertion system with an elastic plunger capable of being reshaped, andhaving a guiding groove in the floor of the cartridge for stabilizingand centering the plunger. Also, U.S. Pat. No. 6,093,193 and U.S. PatentPublication No. 2007-0005135, both to Makker, et al., disclose push rodshaving soft tips.

Despite a number of advances in this field, there remains a need for amore gentle IOL insertion system that reduces the chance of a push rodor plunger from damaging, bypassing or otherwise riding over an IOL asit proceeds through small cartridge lumens.

SUMMARY OF THE INVENTION

One aspect of the present invention is a plunger for an IOL injectorthat can flex elastically, vertically and/or laterally, and is guidedboth vertically and laterally under controlled pre-tension. Because ofthis, the plunger position can be accurately controlled in that thepre-tension keeps the plunger pressed against the guides independent ofslight misalignments arising from the manufacturing or assemblyprocesses. As a result, tolerances can be widened and lateral playbetween the plunger and its guides are eliminated by the pre-tension.

In accordance with one aspect, a system for delivering an intraocularlens (IOL) into the eye of a subject, comprises an IOL injector defininga load chamber for receiving an IOL. A delivery tube communicates withthe load chamber and terminates at a distal tip. The injector furtherincludes a push rod movable through the load chamber for urging the IOLin a distal direction from the load chamber, through the delivery tubeand out of the distal tip in a delivery procedure. A guide within theinjector exerts a camming force on the push rod to transversely urge thepush rod in one or more directions. The load chamber is preferablyadapted to receive an IOL in an orientation such that an axis of the IOLoptic defines a vertical plane, wherein the camming force acts laterallyon the push rod. In one embodiment, the guide comprises a V-shaped slot.The guide may extend linearly in the direction of travel of the pushrod, or otherwise, such as in a spiral path.

Another aspect of the invention is a system for delivering anintraocular lens (IOL) into the eye of a subject comprising an IOLinjector defining a load chamber for receiving an IOL. A delivery tubecommunicates with the load chamber and terminates at a distal tip. Theinjector further includes a push rod movable through the load chamberfor urging the IOL in a distal direction from the load chamber, throughthe delivery tube and out of the distal tip in a delivery procedure. Thepush rod translates along an axis that is angled with respect to theload chamber axis so as to cause a distal end of the push rod to contactthe load chamber and create a compressive bias therebetween. A guidewithin the injector may exert a force on the push rod in a differentplane than the plane in which the compressive bias is created.

The guide may also exert a lateral force on the push rod. In oneembodiment, the guide comprises a V-shaped slot. The guide may extendlinearly in the direction of travel of the push rod, or otherwise, suchas in a spiral or winding path. The distal end of the push rod desirablyfeatures a protrusion that contacts the load chamber proximal from adistal-most extent of the distal end. In one embodiment, a groove withinthe injector receives a distal end of the push rod and against which thepush rod is compressively biased. If the push rod features a protrusion,it may contact the groove within the injector. In one form, the grooveabruptly terminates at a distal end so as to limit distal movement ofthe push rod.

In accordance with a further aspect, the present invention provides anIOL injector system for delivering an intraocular lens (IOL) into theeye of a subject. The system includes an IOL injector defining a loadchamber for receiving an IOL and a delivery tube in communication withthe load chamber and terminating at a distal tip. An inflatable pusherwithin the injector has a proximal end and a distal end, the distal endbeing sized to extend substantially through the injector to the distaltip when the pusher is inflated. A plunger having a piston is movablewithin the injector and adapted to force fluid into and inflate thepusher when moving in a first direction. Desirably, the piston ismovable within the injector toward and away from the proximal end of theinflatable pusher, the piston adapted to force fluid into and inflatethe pusher when moving toward the proximal end thereof. For instance,the plunger may move longitudinally through the injector in asyringe-like manner.

In accordance with one embodiment, the inflatable pusher has a forkeddistal end, or may have a bulbous distal end. The inflatable pusherpreferably has an open proximal end sealed within a cavity of theinjector, and the plunger moves within the cavity to force fluid intothe proximal end. The fluid may be incompressible, such as saline, orcompressible such as air. The system further may include a cartridgethat defines the load chamber and which mates with the injector.

Another aspect of the invention is an inflatable pusher adapted to beused with an injector for urging an intraocular lens (IOL) into the eyeof a subject. The pusher has an open proximal end and a distal end, thedistal end being adapted to extend when the pusher is inflated. Thepusher may have a forked distal end, or a bulbous distal end. In oneform, the pusher has a bellows configuration.

The present invention also provides a method of injecting an intraocularlens (IOL) into the eye of a subject. The method includes providing anIOL injector defining a load chamber and a delivery tube incommunication with the load chamber and terminating at a distal tip, aplunger, and an inflatable pusher having a proximal end and a distalend, the distal end being sized to extend substantially through theinjector to the distal tip when the pusher is inflated. An IOL is placedinto the load chamber of the injector, and the plunger is actuated toforce fluid into and inflate the pusher. Preferably, the plunger ismovable within the injector toward and away from the proximal end of theinflatable pusher, and is adapted to force fluid into and inflate thepusher when moving toward the proximal end thereof. In one embodiment,the plunger moves longitudinally through the injector in a syringe-likemanner. The fluid may be incompressible, such as saline, or compressiblesuch as air. A cartridge may be provided that defines the load chamberand which mates with the injector, and wherein the step of placing theIOL into the load chamber is followed by mating the cartridge with theinjector.

The present invention also provides a method of injecting an intraocularlens (IOL) into the eye of a subject. The method includes providing anIOL injector defining a load chamber and a delivery tube incommunication with the load chamber and terminating at a distal tip, aplunger, and an inflatable pusher having a proximal end and a distalend, the distal end being sized to extend substantially through theinjector to the distal tip when the pusher is inflated. An IOL is placedinto the load chamber of the injector, and the plunger is actuated toforce fluid into and inflate the pusher. Preferably, the plunger ismovable within the injector toward and away from the proximal end of theinflatable pusher, and is adapted to force fluid into and inflate thepusher when moving toward the proximal end thereof. In one embodiment,the plunger moves longitudinally through the injector in a syringe-likemanner. The fluid may be incompressible, such as saline, or compressiblesuch as air. A cartridge may be provided that defines the load chamberand which mates with the injector, and wherein the step of placing theIOL into the load chamber is followed by mating the cartridge with theinjector.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be better understood from thefollowing detailed description when read in conjunction with theaccompanying drawings. Such embodiments, which are for illustrativepurposes only, depict the novel and non-obvious aspects of theinvention. The drawings include the following figures, with likenumerals generally indicating like parts:

FIG. 1 is a sectional view of an exemplary insertion system according toan embodiment of the invention where a plunger advances at a slightangle to the cartridge lumen;

FIG. 2 is a schematic diagram of the insertion system of FIG. 1;

FIG. 3 is a force diagram of the plunger of the system in FIG. 2;

FIG. 4 is a side elevational view of a distal end of a plunger of thepresent invention having a feature on its bottom surface that interactswith the bottom surface of the loading chamber of an inserter;

FIGS. 4A-4E are schematic diagrams showing several possible geometricrelationships between plungers and insertion cartridges;

FIG. 5 is a schematic diagram of an alternative insertion system whichutilizes an upper guide that acts to bias a plunger downward;

FIG. 5A is a cross-section of an exemplary V-shaped guide that may beused in the system of FIG. 5;

FIGS. 6A and 6B are cross-sections of alternative guides that may beused to bias plungers of the present invention;

FIGS. 7A and 7B are schematic views of an alternative mechanism forbiasing an insertion plunger having an uneven cross-section:

FIGS. 8-11 are schematic views of still further alternative mechanismsfor biasing an insertion plunger;

FIGS. 12A-12C are sectional views of a still further aspect of thepresent invention including a non-linear plunger that interacts with thecartridge lumen to bias the plunger;

FIGS. 13A and 13C are sectional views of an alternative pusher rod tipwith deformable wings;

FIG. 14A is a partial longitudinal sectional view of an exemplaryintraocular lens (IOL) insertion system according to an embodiment ofthe invention having an extensible pusher for urging an IOLtherethrough;

FIGS. 14B and 14C are partial longitudinal sectional views of the systemof FIG. 14A showing two stages of advancement of a plunger to forcefluid into the extensible pusher;

FIGS. 15A and 15B are elevational views of an alternative extensiblepusher of the present invention having a bulbous distal end shown inretracted and extended configurations;

FIG. 16 is an elevational view of an alternative extensible pusherhaving a forked distal end;

FIGS. 17A and 17B are elevational views of a further alternativeextensible pusher of the present invention having a bellows structureshown in retracted and extended configurations;

FIG. 18 is an exploded view of an alternative injector system with adisposable cartridge and pusher subassembly that mates with a reusablehandpiece; and

FIGS. 19A and 19B are longitudinal sectional views of an alternativeintraocular lens (IOL) insertion system that utilizes a hydraulicpusher.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention facilitates the process of delivering anintraocular lens (IOL) into a patient's eye using an injector. The IOLis typically implanted using an injector that rolls, folds, or otherwiseconfigures the lens for delivery through a small incision in the eye ina way that reduces trauma and expedites post-surgery healing. The IOL isstored separately and transferred to an injector or cartridge just priorto delivery. The injector or injector/cartridge is used in a manner likea hypodermic needle with the IOL being injected into the eye through adelivery tube. The injector, cartridge and/or delivery tube are firstpartially filled with a liquid or gel lubricating agent, for example aviscoelastic material.

FIG. 1 is a longitudinal sectional view of an insertion system 20according to an embodiment of the invention. The insertion system 20comprises an injector 22 defining and inner bore 24 within whichreciprocates a plunger 26 having a piston 28 on the distal end thatseals against the bore 24. The main portion of the injector 22 issometimes termed a handpiece, and in the illustrated embodimentresembles a syringe with a tubular main body that receives the plunger26. The piston 28 interacts with a push rod 30 having a distal end 32that extends through the inner bore 24.

The injector 22 receives a cartridge 34 on a distal end thereof. Thecartridge encloses an IOL and defines a lumen 36 leading to a distaldelivery tip 38. An opening in the injector 22 enables the push rod 30to extend through the cartridge lumen 36 upon depression of the plunger26. The cartridge 34 is oriented at a slight angle with respect to thelongitudinal axis of the injector 22. In this manner, the distal end 32of the push rod 30 contacts a lower floor of the cartridge lumen 36shortly after entering the cartridge. It should again be stated that thepresent invention is also applicable to systems where the loading anddelivery area are integrated into a hand piece of an injector in aso-called preloaded system.

FIG. 2 is a schematic diagram of the insertion system 20 of FIG. 1, andillustrates travel of the push rod 32 toward the IOL. The cartridge 34is shown having a lower groove 40 within which the distal end 32 of thepush rod 30 is guided. The IOL rests on a floor 42 of the cartridge 34such that it is suspended over the groove 40. The distal end 32 of thepush rod 30 may be forked or otherwise shaped to capture a trailing edge44 of the IOL. The push rod 30 is rigidly connected to the piston 28(FIG. 1) and can only move linearly along its own axis. Desirably, thepush rod 30 is made from a flexible material, such as polypropylene.Because of the angle at which the push rod 30 enters the cartridge andcontacts the groove 40, the push rod 30 flexes and the distal end 32exerts a downward force on the groove. This pre-tension in the push rod30 helps maintain contact with the cartridge lumen and prevent thedistal end 32 from riding over the IOL.

The angle of movement of the push rod 30 with respect to the cartridgelumen 36 is desirably about 10°. The groove 40 is desirably wider thanthe distal end 32 at its proximal end (to the left in FIG. 2), andgradually narrows toward the distal end (to the right) to a width thatis slightly larger than the distal end, preferably about 0.1 mm larger.The distal end 32 is therefore guided by the groove 40 toward the centerof the cartridge 34. The groove may have a rectangular cross-sectionwith vertical sidewalls, in which case the pre-tension is only vertical,imparted by the bottom floor of the groove. Alternatively, the groove 40may have a V-shaped, chevron-shaped, or U-shaped cross-section whichwill impart lateral contact and guidance to the push rod distal end 32.As the push rod 30 and distal end 32 moves distally through thecartridge 34, the bending stress in the push rod increases because ofthe angle at which the push rod travels. The increase bending stressrepresents an increase in the force holding the distal end 32 againstthe inner wall of the cartridge lumen 36, which is desirable because asthe distal end 32 advances through the cartridge the reaction force fromthe IOL increases also. That is, the cartridge lumen 36 graduallynarrows in the distal direction in a funnel-like manner, and more forceis required to push the IOL therethrough. After the distal end 32reaches the end of the groove 40, it continues through the cartridge 34guided by the narrow lumen 36.

FIG. 3 is a force diagram of the plunger of the system in FIG. 2. Thepush rod 30 is idealized has a simple beam having a length L, and thereaction force from the cartridge lumen 36 is indicated by the upperforce arrow F. If the push rod 30 has a height h and base width b, thearea moment of inertia is given as:

I=bh ³/12

The pre-tension force F in a vertical plane is then translated as:

F=3E·I·δ/L ³

where E is the Young's modulus and δ is the deflection of the distal end32.

In this regard, the distal end 32 deflects a lateral distance δ thatequates to the displacement thereof due to contact with the inner wall(e.g., floor) of the cartridge lumen 36 from a point where it would endup if permitted to advance linearly. If the cartridge floor is uneven,the push rod 30 will flex nonlinearly. For example, if a groove 40 isprovided as in FIG. 2, the system may be designed such that the push rod30 does not experience bending, and pre-tension, until the distal end 32rides up onto the cartridge floor 42. Likewise, if the push rod 30advances nonlinearly it will flex in a nonlinear fashion. In all ofthese situations, the pre-tension will maintain contact between thedistal end 32 and the cartridge lumen 36. If, in being urged through thecartridge, the IOL exerts a force on the distal end 32 that isperpendicular to the cartridge and away from the floor of the cartridge,the distal end remains in contact with the cartridge lumen unless thepre-tension force is exceeded. Preferably, the system is designed suchthat the magnitude of deflection, δ, is 1 mm or larger so that thepre-tension is relatively robust.

In one particular embodiment, the push rod 30 is made of a flexiblematerial such as polypropylene or another suitable polymer. The push rod30 is rigidly connected to a sliding fixation point that can only movein an axial direction (idealized as a guiding carriage in FIG. 2). Thepush rod 30 is prevented from rotating about its axis. The length of thepush rod 30 is about 50 mm, and the structure is such that a force F ofabout 0.5 N is required to deflect the distal end 32 laterally 4.3 mm.As mentioned, the push rod 30 desirably advances at an angle of about10° with respect to the axis of the cartridge lumen 36. Initially, thedistal end 32 is not in contact with the cartridge lumen 36, anddesirably contacts the lumen within about 25 mm of travel beforereaching the cartridge distal tip 38 (see FIG. 1).

In various embodiments, the groove 40 may have a rectangular, rounded,V-shaped, or other cross-section. If rectangular, and wider than thedistal end 32, the only channeling force applied to the distal end isvertical. However, if the groove 40 is V-shaped, for example, one or twolateral components of force are also applied to the distal end 32. Inthe latter case, the push rod 30 experiences a pre-tension that bothmaintains it in contact with the groove and also guides it along aparticular path. If the groove 40 is linear, the path is linear.However, in some instances it may be desirable to cause the distal end32 to translate laterally, in which case the groove 40 can be angled,serpentine, or some other configuration. For instance, if rotation ofthe IOL around the axis of the cartridge 36 is desired, the groove 40may curve or spiral around the lumen of the cartridge to cause such IOLrotation.

FIG. 4 is a side elevational view of a distal end 44 of a plunger orpush rod of the present invention having a feature on the bottom surfacethat interacts with an inserter. Depending on the cartridge material andcoating, it may be desirable that the distal-most point of the plunger(or push rod) does not contact the cartridge wall. In some instances,the distal end can scrape or remove material (e.g., a coating) from thecartridge lumen, which can then be transferred to the IOL, creating aproblem after implant. To elevate the distal end 44 the plunger or pushrod includes a feature on its lower surface close to the distal end 44that projects downward and contacts the cartridge lumen. In FIG. 4, abump or protrusion 46 projects downward from the distal end 44 so as tocontact the cartridge floor and maintain a gap a of, for example, 0.1 mmtherebetween. The protrusion 46 is set back from the distal-most pointof the distal end 44 by a distance l, which may vary depending on theangle between the push rod and the cartridge and the size of theprotrusion.

Desirably, the groove 40 blends gradually to the cartridge floor 42 toavoid causing any discontinuity or jamming of movement of the push rod30. However, in some instances a more abrupt ending to the groove 40 maybe preferable. For instance, if the protrusion 46 on the push rod distalend 44 seen in FIG. 4 travels in a groove, forward motion of the pushrod may be halted by interference between the protrusion and a suddenlyending groove. This may be desirable if distal movement of the push rodmust be stopped at a particular point.

FIGS. 4A-4E are schematic diagrams showing several possible geometricrelationships between plungers and insertion cartridges utilizing theprotrusion 46. The protrusion 46 makes contact with the cartridge wall(e.g., floor) which can be maintained with a constant or vertical forceby means of the pre-tension described above. As seen in FIG. 4A, the gapa between the distal end 44 and the cartridge floor will be maintainedwhere the pusher and cartridge floor run parallel. If the distance lbetween the protrusion 46 and the distal tip of the distal end 44 is10-20 mm, overlap of the protrusion with any IOL elements such as opticor haptics is prevented. Conversely, if the protrusion 46 is within 10mm, the distal end 44 will be guided with somewhat more stability.

In FIG. 4B, the push rod advances in parallel to the cartridge floor andthe protrusion 46 maintains the gap a between the distal end 44 and thecartridge wall. In FIG. 4C, the floor of the cartridge is shown angledupward such that the distal end 44 contacts it at point A. Up to thatpoint, the protrusion 46 maintains the gap a. In FIG. 4D the protrusion46 may travel within a groove that is recessed below that portion of thecartridge wall over which the distal end 44 travels. Again, theprotrusion 46 maintains a gap a between the distal end 44 and thecartridge floor. Finally, FIG. 4E illustrates a cartridge having both anincline and a groove. The gap between the distal end 44 and thecartridge wall may be varied by causing the protrusion 46 to travelfirst on the cartridge floor then within a groove. Initially, the gap isshown as the sum of a+b, but after the protrusion 46 enters the groovethe gap is reduced to just a. These alternatives, schematically shown,illustrate basic options for cartridge/injector systems in accordancewith the present invention.

FIG. 5 is a schematic diagram of an alternative insertion system whichutilizes an upper guide 48 to bias a plunger or push rod 50 downward.Again, the push rod 50 translates linearly along an idealized carriage52. The guide 48 contacts and deflects the push rod 50 downward. As seenin an exemplary cross-section in FIG. 5A the guide 40 may have aV-shaped groove 54 within which the push rod 50 translates. The groove54 therefore exerts lateral forces on the push rod 50 and can maintainits centricity, or may be utilized to deflect the push rod laterally.

The distal end 56 of the push rod 50 translates within the cartridgelumen and ultimately contacts the IOL. In the illustrated embodiment,the cartridge has a groove 40 within which the distal end 56 initiallytranslates and a floor 42 on which the IOL rests. Desirably, at themoment the distal end 56 contacts the IOL optic, it still has lateraland vertical freedom of movement. In a preferred embodiment, thecross-section of the push rod 50 is such that it more easily flexeshorizontally than vertically. For example, the height of the push rod 50may be larger than its width. At the moment of engaging the IOL, thepush rod 50 is allowed to align itself because of this freedom ofmovement. Subsequently, as the push rod 50 advances, urging the IOLdistally, the distal end 56 deflects downward under the influence of theupper guide 48 and is compressively biased against the groove 40. Thisadds stiffness and stability.

FIGS. 6A and 6B are cross-sections of alternative guides that may beused to bias plungers/push rods of the present invention. In FIG. 6A, ablunt guide 60 contacts one side of the push rod 62. The guide 60 has aflat face that merely exerts a lateral force on the push rod 62, ratherthan guiding along more than one axis. The guide 60 may be positionedabove the push rod 62, as shown, or on either left or right side so asto bias the push rod in the opposite direction. In FIG. 6B, a push rod64 has chamfered upper corners that conform to a truncated V-shapedgroove 66. The groove 66 channels the push rod 64, but the matchingshapes and truncation help prevent any binding therebetween. Again, thegroove 66 may be formed in a spiral path, for example, to inducerotational movement to the push rod 64.

FIGS. 7A and 7B are schematic views of an alternative mechanism forbiasing an insertion plunger having an uneven cross-section. The firstportion of a push rod 68 is initially in contact with a guide 70. Adistal movement of the push rod 68 causes a second raised portion 72thereon to contact the guide 70. In this manner, the distal end 74 isforced downward and into contact with the cartridge floor so as toprevent riding over the IOL. This cam action between the push rod 68 andthe guide 70 can be accomplished by an uneven push rod, or an unevenguide 70.

FIGS. 8-11 are schematic views of still further alternative mechanismsfor biasing an insertion plunger. In FIG. 8, a straight push rod 76 ispressed down after a distal end 78 enters a lumen of a cartridge 80. Inthis regard, a moving guide may be utilized, such as one which istriggered by linear movement of the push rod 76. In FIG. 9, a curvedpush rod 82 has a distal end 84 that is lifted just prior to entering alumen of the cartridge 86. Alternatively, the cartridge may be depressedas indicated by the downward arrow, and may be biased upward by a springforce, schematically shown as two springs 88. FIGS. 10A and 10B aresimilar to FIG. 9, but the cartridge 86 pivots about hinge point 90 andis biased upward at its rear end by only one spring 92. The curved pushrod 82 enters the lumen after depressing the rear end of the cartridge86, which is then released to create a compressive bias between thedistal end 84 and the lumen of the cartridge 86. After advancing withinthe lumen of the cartridge 86 such that the distal end 84 passes thehinge point 90, a thicker region or cam 94 on the push rod 82 contactsthe cartridge lumen and maintains a downward pressure thereto. Thishelps maintain a compressive bias between the distal end 84 and thelumen of the cartridge 86. Finally, Figures 11A-11C illustrates a curvedpush rod 96 having a protrusion 98 thereon. Interference between theprotrusion 98 and a guide 100 associated with the injector or thecartridge lifts the distal end 102 so that it enters the lumen of thecartridge 86. Once in the cartridge 86, the protrusion 98 passes theguide 100, allowing the curved push rod 96 to exert a downward force onthe cartridge lumen, and the bias or pre-tension is established.

FIGS. 12A-12C are sectional views of a still further aspect of thepresent invention including a non-linear plunger 104 that interacts witha cartridge lumen 106 to bias the plunger against the lumen. Morespecifically, the plunger 104 in its unstressed condition has a curvedor, as illustrated, angled configuration, which is bent at an angle α ata point B. A distal portion terminating in the distal end 108 isdirected downward. When the plunger 104 enters the cartridge lumen 106,uppermost point B enters a groove 110 in the ceiling of the lumen. Theplunger 104 is thus guided by the groove 110, and straightens out byvirtue of simultaneous contact between the distal end 108 and floor ofthe cartridge lumen 106 (i.e., the angle α increases). The elasticdeformation of the plunger 104 creates a vertical downward force thatthe distal end 108 exerts on the floor of the cartridge lumen 106.Again, lateral forces exerted on the plunger 104 by the guide groove 110maintains the plunger centered within the lumen.

FIGS. 13A and 13C are sectional views of an alternative pusher rod tip112 with deformable wings 114. The rod tip 112 is seen in a relaxedstate in FIG. 13A and after having been advanced through an injectorlumen 116 in FIG. 13B. As the lumen 116 gets smaller, the wings 114 willdeform, thus biasing the rod tip 112 and adding stiffness to the system.More precisely, the wings 114 tend to curl up to conform to the shape ofthe injector lumen 116, and in doing so push the central portion of therod tip 112 in one direction, for instance to the bottom of the lumen asshown.

In addition to biasing and guiding push rods/plungers, the presentinvention may also incorporate an extensible member that helps preventbinding of the IOLs. A push rod that is guided for an initial portion ofits travel may also incorporate an extensible member to finish pushingthe IOL the last portion. Variations of extensible members are shown anddescribed below, and it should be understood that the variousembodiments may be combined with the several push rod embodimentsdescribed above.

FIG. 14A is a partial longitudinal sectional view of an insertion system120 according to another embodiment of the invention. The insertionsystem 120 comprises an injector 122 defining an inner bore 124 withinwhich a plunger 126 reciprocates. The main portion of the injector 122is sometimes termed a handpiece, and in the illustrated embodimentresembles a syringe with a tubular main body that receives the plunger126 having a piston 128 on the distal end that seals against the bore124.

An extensible pusher 130 is positioned at the distal end of the bore124. The pusher 130 includes an extensible distal portion 132 and anopen proximal end 134. The distal portion 132 terminates at a distal end136, which in the illustrated embodiment is rounded. In a preferredembodiment, the extensible pusher 130 comprises an inflatable balloonformed of a material that permits significant elongation. For example,the pusher 130 may be formed of thin-walled silicone rubber. In apreferred embodiment, the distal end of the injector 122 defines afunnel shape which mirrors the relaxed shape of the extensible pusher130.

In the insertion system 120 axial movement of the plunger 126 translatesinto axial movement of the extensible pusher 130. One benefit may bethat a predetermined displacement of the plunger 126 may be converted togreater displacement of the pusher tip, or visa versa. If the former,the axial dimension of the injector can be reduced.

The distal end of the injector 122 includes a cavity that closelyreceives an IOL injector cartridge 140. As mentioned above, someinsertion systems do without the cartridge and thus the term injectorfor those encompasses certain structural aspects associated with theillustrated cartridge. The cartridge 140 defines a load chamber 142within which is shown in IOL. It through bore within the cartridge 140leads to a delivery channel 144 and the distal opening 146. As is knownin the art, the IOL can be urged through the cartridge 140 and from thedistal opening 146 into the eye of a patient.

With reference to FIGS. 14B and 14C, an operator depresses plunger 126with his or her fingers to cause the piston 120 to translate distallywithin the injector bore 124. As the plunger 126 advances, the piston128 forces fluid within the bore 124 into the open end 134 of theextensible pusher 130. As a result, the extensible distal portion 132elongates such that the distal tip 136 passes through an opening 150 andinto the load chamber 142 of the cartridge 140. Further advancement ofthe plunger 126 displaces the distal end 136 into contact with the IOL,thus urging the IOL through the cartridge 140. The flexible nature ofthe pusher material helps prevent damage to the IOL in comparison to arigid pusher rod.

The working fluid provided within the bore 124 of the injector 122 maybe incompressible, such as the saline or a viscoelastic medium, orcompressible such as air or nitrogen. Desirably, the extensible pusher130 is constructed with a significant safety factor so as to ensure noruptures occur. For instance, the extensible pusher 130 can be formedwith limited elasticity. However, small openings in the distal end 136may permit a controlled release of a small amount of the working fluid,such as a viscoelastic medium. In the absence of such openings, one orboth of the pusher 130 and cartridge lumen are desirably coated with alubricious substance such as a viscoelastic medium to reduce frictionand promote smooth extension of the inflating pusher. Further, aninflation pre-load may be provided such that the extensible pusher 130is partly inflated, or at least is inflated to a point just before thedistal portion 132 begins stretching. This reduces the required amountof travel of the plunger 126.

Although a syringe-like injector 122 having a linearly movable plunger126 is shown, other ways for forcing fluid into an extensible pusher arecontemplated. Any actuator having a piston movable within the injectorbore adapted to force fluid into and inflate the pusher when moving in afirst direction may be used. For example, instead of being linearlydepressed, the plunger 126 may be rotated so as to translate axially,thus increasing the sensitivity of the extension of the pusher 130.Likewise, the linearly movable pusher 126 may be replaced with atrigger-like actuator or lever which moves the piston 128. Those ofskill in the art will understand that the invention is not limited bythe illustrated syringe embodiment.

Similarly, the pusher 130 shown as a funnel-like balloon having an openproximal end 134. However, it may be necessary to provide some type ofrigid support or flange at the proximal end 134 to prevent the pusherfrom moving distally through the injector. In this regard, the term openproximal end with reference to the end 134 encompasses variations thatinclude an opening to the bore 124 that permits fluid to travel from thebore to the interior of the pusher 130.

Now with reference to FIGS. 15A and 15B, an alternative pusher 160 isshown in retracted and extended configurations, respectively. The pusher160 again includes an open proximal end 162 and an extensible distalportion 164 terminating in a distal end 166. Rather than being roundedor tapered, as in the first embodiment, the distal end 166 is slightlyenlarged from the remainder of the distal portion 164 so as to form abulbous end. Various shapes of balloons can be formed for use as theextensible pusher 160, such as the bulbous end shown, or one which has aflat distal face. Such a configuration helps ensure that the pushersuccessfully urges the IOL from the cartridge, and prevents the IOL frombecoming wedged between the pusher and the inner lumen of the cartridge.

FIGS. 15A and 15B also illustrate the change in length between theretracted configuration L₁ and the extended configuration L₂. In apreferred embodiment, the pusher 160 is made a silicone rubber having ahigh elongation factor such that L₂/L₁ is at least 2, and morepreferably about 4. Of course, the lengths to which the pusher 160 mustextend depends on its positioned relative to the loaded IOL a, and thelength of the injector or cartridge delivery tip. Those of skill in theart will understand that a variety of different extensible pushers aresuitable for the present invention.

In an alternative embodiment shown in FIG. 16, an extensible pusher 170has a forked distal end 172. A forked shape is sometimes used in rigidinjector rods to capture a trailing end of the IOL optic. Because of theflexible/inflatable nature of the pusher 170, the forked distal end 172helps prevent damage to sometimes delicate IOLs. A forked end 172 alsoenables rotational manipulation of the IOL. In the latter instance, ameans of rotating the pusher 170 may be included.

FIGS. 17A and 17B illustrate a still further alternative extensiblepusher 180 having a bellows configuration. In particular, the pusher 180includes a mid-section 182 having pleats or folds 184. In thisconstruction, the material used for the wall of the pusher need not bequite as extensible, merely flexible. Of course, there are otherconfigurations similar to a bellows designed, such as a balloon having amiddle section that has been folded upon itself.

FIG. 18 shows exploded an alternative injector system 200 with adisposable cartridge and pusher subassembly 202 that mates with areusable handpiece 204. A male end 206 of the handpiece 204 fluidlyseals against a female end 208 of the subassembly 202. The variousworking parts of the system are as described above. A cartridge 210 maybe separable from the subassembly 202 as shown and described above, ormay be incorporated therein. A surgeon selects an IOL and loads it intothe cartridge 210, then mates the subassembly 202 with the handpiece 204and injects the IOL as before.

The present invention thus provides an improved pusher for urging an IOLthrough an injector or cartridge that is more gentle to the IOL. Forthat matter, the distal end of the various pusher described herein maybe capped with a very soft material to further enhance the gentlehandling of the IOL.

In a still further embodiment, FIGS. 19A and 19B illustrate analternative intraocular lens (IOL) insertion system 220 that utilizes ahydraulic pusher. Specifically, a plunger 222 having a seal 224reciprocates within a chamber of an injector 226. A distal rod 228extends within a smaller lumen 230 leading to a cartridge lumen 232 (oran extension of the injector handpiece in unitary systems). A hydraulicfront 234 of fluid within the chamber will urge the IOL forward morerapidly than a solid plunger tip because of the difference incross-sections A₁ and A₂. That is, the plunger 222 and rod 228 translatea distance x₁, while at the same time the IOL travels a longer distancex₂. The fluid is desirably a viscous biocompatible fluid such as aviscoelastic medium (e.g., Healon). If the fluid leaks around the IOLthe tip of the distal rod 228 physically impels the IOL forward.

It is not the intention to limit this invention to the particularembodiments disclosed. On the contrary, the intention is to covermodifications and alternate constructions coming within the spirit andscope of the invention as generally expressed by the following claims,which particularly point out and distinctly claim the subject matter ofthe invention.

1. A system for delivering an intraocular lens (IOL) into the eye of asubject, comprising: an IOL injector defining a load chamber forreceiving an IOL and a delivery tube in communication with the loadchamber and terminating at a distal tip, the injector further includinga push rod movable through the load chamber for urging the IOL in adistal direction from the load chamber, through the delivery tube andout of the distal tip in a delivery procedure; and a guide within theinjector that exerts a camming force on the push rod to transverselyurge the push rod in one or more directions.
 2. The system of claim 1,wherein the load chamber is adapted to receive an IOL in an orientationsuch that an axis of the IOL optic defines a vertical plane, wherein thecamming force acts laterally on the push rod.
 3. The system of claim 2,wherein the guide comprises a V-shaped slot.
 4. The system of claim 2,wherein the guide extends linearly in the direction of travel of thepush rod.
 5. The system of claim 2, wherein the guide extends in aspiral path.
 6. A system for delivering an intraocular lens (IOL) intothe eye of a subject, comprising: an IOL injector defining a loadchamber for receiving an IOL and a delivery tube in communication withthe load chamber and terminating at a distal tip, the injector furtherincluding a push rod movable through the load chamber for urging the IOLin a distal direction from the load chamber, through the delivery tubeand out of the distal tip in a delivery procedure, wherein the push rodtranslates along an axis that is angled with respect to the load chamberaxis so as to cause a distal end of the push rod to contact the loadchamber and create a compressive bias therebetween.
 7. The system ofclaim 6, further including a guide within the injector that exerts aforce on the push rod in a different plane than the plane in which thecompressive bias is created.
 8. The system of claim 7, wherein the guidecomprises a V-shaped slot.
 9. The system of claim 7, wherein the guideextends linearly in the direction of travel of the push rod.
 10. Thesystem of claim 7, wherein the guide extends in a spiral path.
 11. Thesystem of claim 6, wherein the distal end of the push rod features aprotrusion that contacts the load chamber proximal from a distal-mostextent of the distal end.
 12. The system of claim 6, further including agroove within the injector that receives a distal end of the push rodand against which the push rod is compressively biased.
 13. The systemof claim 12, wherein the distal end of the push rod features aprotrusion that contacts the groove within the injector.
 14. The systemof claim 13, wherein the groove abruptly terminates at a distal end soas to limit distal movement of the push rod.
 15. A system for deliveringan intraocular lens (IOL) into the eye of a subject, comprising: an IOLinjector defining a load chamber for receiving an IOL and a deliverytube in communication with the load chamber and terminating at a distaltip; an inflatable pusher within the injector that has a proximal endand a distal end, the distal end being sized to extend substantiallythrough the injector to the distal tip when the pusher is inflated; anda plunger having a piston movable within the injector and adapted toforce fluid into and inflate the pusher when moving in a firstdirection.
 16. The system of claim 15, wherein the piston is movablewithin the injector toward and away from the proximal end of theinflatable pusher, the piston adapted to force fluid into and inflatethe pusher when moving toward the proximal end thereof.
 17. The systemof claim 16, wherein the plunger moves longitudinally through theinjector in a syringe-like manner.
 18. The system of claim 15, whereinthe inflatable pusher has a forked distal end.
 19. The system of claim15, wherein the inflatable pusher has a bulbous distal end.
 20. Thesystem of claim 15, wherein the inflatable pusher has an open proximalend sealed within a cavity of the injector, and the plunger moves withinthe cavity to force fluid into the proximal end.
 21. The system of claim15, wherein the fluid is incompressible.
 22. The system of claim 21,wherein the fluid is saline.
 23. The system of claim 15, wherein thefluid is compressible.
 24. The system of claim 15, further including acartridge that defines the load chamber and which mates with theinjector.
 25. The system of claim 15, wherein the cartridge and pusherare provided in a disposable subassembly that mates with a handpiece ofthe injector.
 26. An inflatable pusher adapted to be used with aninjector for urging an intraocular lens (IOL) into the eye of a subject,the pusher having an open proximal end and a distal end, the distal endbeing adapted to extend when the pusher is inflated.
 27. The system ofclaim 26, wherein the inflatable pusher has a forked distal end.
 28. Thesystem of claim 26, wherein the inflatable pusher has a bulbous distalend.
 29. The system of claim 26, wherein the inflatable pusher has abellows configuration.
 30. A method of injecting an intraocular lens(IOL) into the eye of a subject, comprising: providing an IOL injectordefining a load chamber and a delivery tube in communication with theload chamber and terminating at a distal tip, a plunger, and aninflatable pusher having a proximal end and a distal end, the distal endbeing sized to extend substantially through the injector to the distaltip when the pusher is inflated; and placing an IOL into the loadchamber of the injector; actuating the plunger to force fluid into andinflate the pusher.
 31. The method of claim 30, wherein the plunger ismovable within the injector toward and away from the proximal end of theinflatable pusher, the plunger adapted to force fluid into and inflatethe pusher when moving toward the proximal end thereof.
 32. The methodof claim 31, wherein the plunger moves longitudinally through theinjector in a syringe-like manner.
 33. The method of claim 30, whereinthe fluid is incompressible.
 34. The method of claim 33, wherein thefluid is saline.
 35. The method of claim 30, wherein the fluid is air.36. The method of claim 30, further including a cartridge that definesthe load chamber and which mates with the injector, and wherein the stepof placing the IOL into the load chamber is followed by mating thecartridge with the injector.